I would replace the battery as there cheap mine is starting to take a little bit to get going as well and I feel it's the battery as mine take a little bit to start even after i replaced my starter motor ( had to replace my starter on a seperate issue)The cold crank amps might be running low due to the age of the battery.

Or even just find a freind with a similar battery from a new car and test his battery

If you open the trunk compartment youll see a little window on the battery. In this window is a green diode. It will turn to yellow and subsequently red as an indication of battery health, and as a way of seeing when to change the battery.